MULTIPLEXING_BCD_SWITCHES

Published:2009/7/7 21:40:00 Author:May | From:SeekIC

Multiplexing technique reduces number of interconnections between thumbwheel switches and counters, displays, or industrial control equipment being programmed remotely Ten decades of BCD switches require only 10 interconnections, as compared to 50 without multiplexing, All 10outputs of low-cost single-pole decade switches are paralleled. with wiper arm connections being brought out separately Parallel outputs are fed into simple encoder using four NAND gates to generate4-bit BCD output code. Wiper of each switch is addressed from active low open-collector decoder. In operation,3-bit input address determines which decade switch is addressed, and switch position then determines which encoder NAND gates are activated.-E. Breeze, Putting the, ”Thumb″ on Thumbwheel Switch Multiplexing, EDN Magazine, Aug,1,1972, p56.



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